Primate retina contains a variety of ganglion cell types which can show different morphologic forms, retinal distributions, functional properties, and central projections. the developmental factors which give rise to the differentiation of primate retinal ganglion cells into distinct types remain largely unknown although retinal ganglion development in cats and rats has been studied intensively in recent year. The results of these studies suggest that both intrinsic genetic mechanisms and extrinsic influences of the cell's retinal environment contribute to the maturation of the structure and function of retinal ganglion cells. The experiments in this application are designed to increase our understanding of primate retinal ganglion cell development, structure, function, projections, and distribution. The effects of neonatal damage to the visual pathways will be clarified as will the effects of neonatal cortical damage upon the development of the retinotectal pathway. Experiment 1 is designed to determine the extent to which overall ganglion cell density and class specific mechanisms contribute to the development of the nonrandom, territorial distribution of retinal ganglion cell dendrites as well as normal dendritic maturation (dendritic branch and spine loss). Whether or not interactions between different classes of retinal ganglion cells during development is required for retinal ganglion cells and the cells in the superior colliculus to which they project to develop normal receptive fields properties will also be determined. Experiment 2 is designed to determine the anatomical and physiological properties of the unique retinal ganglion cells in and around the foveal pit of monkeys. Experiment 3 is designed to clarify the mechanisms mediating foveal development and the development of the morphology and receptive field properties of foveal ganglion cells. These studies will be carried out using standard techniques including horseradish peroxidase histochemistry, DiI fluorescence labeling, reduced silver staining, computerized morphometric analysis, intraocular, extracellular single unit recordings and computer controlled visual stimulation, and data analysis.